Joey and Chandler are at the coffeehouse. Chandler's been sent there because he was getting in the way of Monica's decorating for Rachel's birthday party. Rachel and Ross walk in, Joey starts singing Happy Birthday and Rachel tells him to stop it or Gunther will wanna hug her. They are then introduced to Molly who's Emma's new nanny.
At Phoebe's apartment, she's talking to Mike when he discovers a rat in the cupboard. Phoebe isn't at all surprised, and tells Mike that he's her pet rat called Bob. Mike wants Phoebe to get rid of Bob.
At Ralph Lauren, Rachel thanks Gavin for looking after Emma, but gets annoyed with him for staring at Heather's ass when she's apologizing. He then brings up Tag, which Rachel doesn't like.
At the coffeehouse, Joey is flirting with Molly and Ross tells him to stay away, which makes him want her more. Over at Phoebe's apartment, Mike is setting rat-traps which Phoebe tries to stop. When she finds him, she realizes that he's a girl and she has mouse babies.
At Monica's and Chandlers apartment Ross want Chandler to watch Joey and make sure he doesn't go after Molly. Ross leaves, and then Chandler bumps into Joey who's trying to see Molly.
At Rachel's office Rachel and Gavin are arguing, when Monica comes in and invites him to her birthday party.
At Rachel's party, she's still complaining. She is then really annoyed when she finds out that Phoebe and Mike brought their rats to her party. Phoebe then leaves to look after them.
Ross finds out that Molly and Joey have went away and goes after them. Ross storms in to his apartment and lectures Joey. While he's doing this, there's a knock on the door and it's her girlfriend. They make out.
At Phoebe's, Mike's complaining about looking after the rats. They realize how many rats they'll have if the rats keep mating and they decide to give them up, while they are discussing this Phoebe lets it slip that she gave birth to her brothers triplets.
Back at Monica's, Monica and Rachel are talking on the balcony. Then Gavin shows up, with a present which is a green scarf. They then lean in and kiss.